Cocaine and other psychostimulant drugs exert their addicting actions by interacting with specific neurochemicals in brain. One of the most recently discovered neurochemicals that cocaine alters is called "CART," for (Cocaine and Amphetamine Regulated Transcript). The goal of this project is to elucidate the role of CART peptides in the mechanisms of action of psychostimulant drugs in the brain. Preliminarily, we have evidence that CART peptides, when injected into the brain, produce psychostimulant- like behavioral effects. This suggests that these peptides mediate or modulate the action of psychostimulant drugs and therefore may help explain their action and could be a target for novel medications for cocaine abusers. Additional data indicate that CART peptides may be neurotransmitters in brain and involved in a variety of important functions including feeding, sexual behavior, endocrine and stress control, and cardiovascular control.